The present invention relates to double-balanced diode mixer circuits, and more particularly, to such mixer circuits suitable for use in the microwave frequency range.
Double-balanced diode mixer circuits are known and recently means have been proposed for obtaining excellent cross modulation characteristics by applying a self-bias to the mixer diodes in a manner utilizing the locally generated signals.
With these circuits, good characteristics can be obtained for the signals of relatively low frequencies, for example, for signals of frequencies lower than 1000 MHz. The characteristics, however, are degraded when even one of the signals to be treated has a frequency of several thousand MHz. Namely, the signals passing through the mixer diodes are attenuated by the stray capacitance or inductance in the circuit, whereby cross modulation characteristics, NF characteristics and intermodulation characteristics of the circuit are degraded. Therefore, it has been desired to improve such defects.